This invention relates generally to a construction machine with an operator""s cab, for example, a hydraulic excavator, a hydraulic crane and the like, and more particularly to a construction machine which has an operator""s cab supported on a frame of the machine in a vibration damped state.
Generally, a hydraulic excavator as a construction machine with an operator""s cab is largely constituted by a truck body, a rotary upper body which is rotatably mounted on the truck body, and a working mechanism which is provided on the upper rotary body for upward and downward lifting movements. Provided on a frame of the upper rotary body is an operator""s cab which accommodates control instruments and devices to be manipulated by an operator in controlling operations of the truck body and working mechanism, and an operator""s seat to be occupied by an operator.
In connection with hydraulic excavators as mentioned above, for instance, Japanese Laid-Open Patent Publication No. H5-125745 discloses a hydraulic excavator having an operator""s cab mounted on a support frame in a vibration damped state, by the use of anti-vibrational mounts in the form of liquid-sealed rubber mounts which are interposed in four corner portions between the support frame and the operator""s cab in an attempt to suppress transmission of vibrations from the frame to the cab during a ground excavating operation or when the machine is in travel.
In the case of the prior art hydraulic excavator with the arrangements just mentioned, vibrations which occur to the support frame during a traveling or excavating operation, are absorbed by vertical flexures of the anti-vibrational mounts to prevent direct transmission of the vibrations to the operator""s cab. This contributes to improve the amenity of the operator""s cab as well as the maneuverability of various control levers and the like.
Among hydraulic excavators of various classes, the large-size hydraulic excavators which are used, for example, in excavating a large quantity of earth at open mining sites, are usually constructed in a different concept. Namely, in the construction of large-size hydraulic excavators, there has been a trend toward giving top priority to the machine durability rather than the amenity of the operator""s cab because, in the case of machine trouble, repair work could take an enormously long time. For this reason, usually little attention is paid to the amenity of the operator""s cab in the construction of large-size hydraulic excavators.
Especially in the case of a hydraulic excavator of the so-called high mount cab type, a vertical or upright bed frame is provided on a main frame which constitutes a bottom portion of a rotary body, and an operator""s cab is mounted on top of the bed frame. In a high mount cab type hydraulic excavator, due to the provision of the bed frame, the operator""s cab is located in a position which is largely spaced away from a truck body in an upward direction, and vibrations which occur when the machine is in travel or which occur during an excavating operation are transmitted to the cab through the bed frame, thereby putting the cab in conspicuous vibrational movements.
In this regard, even for large-size hydraulic excavators, it is conceivable to employ the above-mentioned anti-vibrational mounts between a bed frame and a cab structure to suppress transmission of vibrations from the bed frame to the cab and to improve the amenity of the cab in a similar manner.
However, large-size hydraulic excavators which are often used for a horizontal excavating operation by a loader bucket, have an inherent problem that vibrations in back and forth directions as well as vibrations in lateral directions (both vibrations hereinafter referred to collectively as xe2x80x9chorizontal vibrationsxe2x80x9d for brevity) are more likely to be transmitted to the cab during excavating operations. Nonetheless, the prior art anti-vibrational mounts which are designed to absorb mainly vertical vibrations, are arranged to have relatively low rigidity against vertical vibrations and relatively high rigidity against horizontal vibrations.
Therefore, in the case of high mount cab type hydraulic excavators, the conventional anti-vibrational mounts which have high rigidity against horizontal vibrations, are incapable of absorbing horizontal vibrations which occur to a bed frame at the time of ground excavating operations. Accordingly, as shown in FIG. 17, if a bed frame 101 is put in vibrations in a back and forth direction (in the direction of arrow a), a cab 102 is largely shaken on the bed frame 101 by pitching (back and forth vibrations) as indicated by arrow b to deteriorate the amenity of the cab as well as the maneuverability of control levers or other devices to a considerable degree. On the other hand, if the bed frame is put in vibrations in a lateral direction, the cab 102 is also largely shaken by rolling (rightward and leftward vibrations). A further problem is that, when the rotary body is put in a rotational movement, the cab 102 is shaken by yawing (vibrations in a rotational direction).
In view of the problems with the prior art as mentioned above, it is an object of the present invention to provide a construction machine with an operator""s cab on a frame, which is arranged to suppress transmission of vibrations from the frame to the cab.
In accordance with the present invention, the above-mentioned problems are solved by the provision of a cab support which is applicable to a construction machine with an operator""s cab, basically including a support frame, an operator""s cab mounted on the support frame and internally defining an operating room, and four anti-vibrational mounts interposed in four corner portions between the support frame and the cab and adapted to support the cab in such a manner as to suppress transmission of vibrations from the frame to the cab.
More particularly, according to the present invention, there is provided a construction machine with an operator""s cab, which is characterized by the provision of: four anti-vibrational mounts each constituted by a laminated rubber body having relatively high rigidity against vibration in a vertical direction and relatively low rigidity against vibration in a horizontal direction; and four vibration attenuating devices located in four corner portions between the frame and cab and in cooperative positions relative to the anti-vibrational mounts to attenuate horizontal vibrations transmitted to the cab.
With the arrangements just described, when the frame is put in vibration in a lateral direction, the laminated rubber bodies of the respective anti-vibrational mounts are caused to flex largely in a horizontal direction, thereby suppressing transmission of vibration from the frame to the cab. At this time, even if the vibration of the frame is transmitted, the cab is simply put in horizontal parallel movements and prevented from being shaken largely by pitching or rolling vibrations because the laminated rubber bodies of the anti-vibrational mounts have high rigidity against vibrations in vertical directions. Besides, even if horizontal residual vibrations occur to the cab due to resilient restoring forces of the laminated rubber bodies which are flexed by vibrations of the frame, such residual vibrations can be damped by the respective vibration attenuating devices.
In this instance, according to the present invention, two of the vibration attenuating devices, which are located in front portions of the cab, are mounted in a horizontal plane and in an angular posture such that respective longitudinal axes are intersected with each other on the front side of the cab, while the remaining two vibration attenuating devices, which are located in rear portions of the cab, are likewise mounted in a horizontal plane and in an angular posture such that respective longitudinal axis are intersected with each other on the rear side of the cab.
Further, each one of the vibration attenuating devices according to the present invention is so arranged as to have a longitudinal axis thereof located in a circumscribing position relative to an imaginary ellipse drawn around a bottom center portion of the cab.
With the arrangements just described, the respective vibration attenuating devices are mounted in a horizontal plane and in an angular posture which is inclined relative to back and forth and transverse directions of the cab. Therefore, when the cab is put in vibrations in back and forth directions or in lateral directions, these vibrations can be effectively damped by the vibrations attenuating devices. Further, the vibration attenuating devices also function to effectively suppress yawing movements which may occur to the cab as a result of a rotational movement.
Further, in one particular form of the present invention, the frame is a main frame constituting a bottom portion of a rotary body of the machine, and the cab is supported on the main frame through the anti-vibrational mounts.
In this instance, when the frame is vibrated during a vehicular traveling operation or a ground excavating operation of the machine, transmission of the vibration of the frame to the cab can be suppressed by the respective anti-vibrational mounts.
Further, in another form of the present invention, the frame is composed of a main frame constituting a bottom portion of a rotary body of the machine and a bed frame standing vertically on the main frame, and the cab is supported on the bed frame through the anti-vibrational mounts.
In this instance, the respective anti-vibrational mounts function to suppress transmission of vibrations from the frame to the cab through the bed frame, thereby preventing the cab from being largely shaken on the bed frame.
Furthermore, in a preferred form of the present invention, each one of the anti-vibrational mounts is constituted by a laminated rubber body having a number of rubber layers laminated alternately and in parallel relation with a number of thin steel sheet layers, an upper mounting plate securely fixed to an upper end of the laminated rubber body, and a lower mounting plate securely fixed to lower end of the laminated rubber body.
In this instance, preferably the frame and the lower mounting plate of each anti-vibrational mounts are securely fastened to each other by the use of bolts, and stud bolts are fixedly provided either on the side of the cab or on the side of the upper mounting plate of the anti-vibrational mounts and adapted to be received in bolt holes provided either on the side of the upper mounting plate or on the side of the cab.
With the arrangements just described, at the time of mounting the cab on the frame through the anti-vibrational mounts, the cab can be automatically set in position relative to the anti-vibrational mounts simply by fastening the lower mounting plates of the anti-vibrational mounts securely to the frame by means of bolts and inserting the stud bolts, which are provided either on the side of the upper mounting plates of the anti-vibrational mounts or on the side of the cab, into bolt holes which are provided opposingly either on the side of the cab or on the side of the upper mounting plates of the anti-vibrational mounts.
Further, in another preferred form of the present invention, the cab and the upper mounting plate of each anti-vibrational mounts are securely fastened to each other by the use of bolts, and stud bolts are fixedly provided either on the side of the frame or on the side of the lower mounting plate of the anti-vibrational mounts and adapted to be received in bolt holes provided either on the side of the lower mounting plate or on the side of the frame.
With the arrangements just described, at the time of mounting the cab on the frame through the anti-vibrational mounts, each one of the anti-vibrational mounts can be automatically set in position relative to the frame, upon inserting the stud bolts, which are provided either on the side of the lower mounting plates of the anti-vibrational mounts or on the side of the frame, into bolt holes which are provided opposingly either on the side of the frame or on the side of the lower mounting plates of the anti-vibrational mounts.
In another preferred form of the present invention, stud bolts are fixedly provided in the lower mounting plate of each anti-vibrational mounts and adapted to be received in bolt holes provided in the frame, and stud bolts are fixedly provided in the upper mounting plate of the anti-vibrational mounts and adapted to be received in bolt holes provided on the part of the cab.
With the arrangements just described, at the time of mounting the cab on the frame through the anti-vibrational mounts, the respective ones of the anti-vibrational mounts can be automatically set in position relative to the frame and the cab, upon inserting stud bolts, which are provided on the lower and upper mounting plates of the anti-vibrational mounts, into bolt holes which are provided opposingly on the side of the frame and the cab, respectively.
In still another preferred form of the present invention, the frame and the lower mounting plate of each anti-vibrational mount are securely fastened to each other by the use of bolts, and an intermediate connecting plate is attached to the upper mounting plate of the anti-vibrational mount, the intermediate connecting plate having stud bolts adapted to be received in bolt holes provided on the part of the cab.
With the arrangements just described, at the time of mounting the cab on the frame through the anti-vibrational mounts, each of the anti-vibrational mounts which have the respective lower mounting plates fastened to the frame by means of bolts, can be automatically set in position relative to the cab upon inserting the stud bolts on the intermediate connecting plate, which is attached to the upper mounting plate of each anti-vibrational mount, into bolt holes which are provided opposingly on the side of the cab. Besides, in this case, at the time of replacement of an anti-vibrational mount, it can be easily extracted in a horizontal direction as soon as the upper mounting plate is removed from the intermediate connecting plate, without being obstructed by the stud bolts.
Furthermore, in another preferred form of the present invention, the cab and the upper mounting plate of each of the anti-vibrational mounts are securely fastened to each other by the use of bolts, and an intermediate connecting plate is attached to the lower mounting plate of the anti-vibrational mount, the intermediate connecting plate having stud bolts adapted to be received in bolt holes provided on the side of the frame.
With the arrangements just described, at the time of mounting the cab on the frame through the anti-vibrational mounts, the anti-vibrational mounts can be automatically set in position relative to the frame, upon inserting the stud bolts of the intermediate connecting plate, which is attached to the lower mounting plate of each anti-vibrational mounts, into bolt holes which are provided opposingly on the side of the frame. Besides, in this case, at the time of replacement of an anti-vibrational mount, it can be easily extracted in a horizontal direction after detaching the lower mounting plate from the intermediate connecting plate, without being obstructed by the stud bolts.